BREECH FOR A GUN WHICH IS ABLE TO OPERATE WITH TWO DIFFERENT BREECH BLOCKS

Abstract: A modular concept for a gun which uses a breech conversion kit allows the firing of cased and caseless ammunition with the same gun. The cannon has a breech mechanism (10) which includes a first sliding breech-block (19) which engages the rear end (15) of a cartridge case in the firing position. Said first sliding breech-block (19) is interchanged for a second sliding breech-block (21) when firing caseless ammunition. Said second breech-block is in contact with a sealing member (23) which is mounted pivotally on an axis (27) which is located on the upper face of breech ring (11).

Description: BREECH FOR A GUN WHICH IS ABLE TO OPERATE WITH TWO DIFFERENT BREECH BLOCK THIS invention relates to the breech of a cannon or the like. Two types of ammunition are generally available for cannons: a first type known as cased ammunition in which the case carries the propeilant charge, and a second type known as caseless ammunition which does not have such a case and for which the propeilant charge has to be loaded separately into the firing chamber of the cannon. The breech of the conventional cannon is adapted to handle only one of the aforesaid types of ammunition and different cannons are accordingly employed for shooting cased and caseless ammunition. The conventional cannon breech usually includes a sliding block which is slidably movable in a transverse direction relative to the longitudinal axis of the firing chamber of the cannon from one position (hereafter referred to as the operative position) where it serves to seal off the rear end of the firing chamber of the cannon when the cannon is in the firing position, to a second position (hereafter referred to as inoperative position) where it does not. Where the cannon is of the type which fires cased ammunition, the said sliding block serves to support the rear end of an ammunition case loaded into the firing chamber of the cannon and to effect the aforesaid sealing off action in cooperation with such rear end. Where the cannon is of the type which employs caseless ammunition, an additional sealing means has to be employed for sealing off the rear end of the firing chamber. It will be appreciated that because the breech of the conventional cannon is adapted only to fire one of the aforesaid two types of ammunition, it restricts the usefulness of such a cannon. It is accordingly an object of this invention to provide an arrangement with which this problem can be overcome or at least minimised. According to the invention a breech for a cannon is provided which includes two interchangable sliding blocks, a first one which can in conventional manner in the operative position support and cooperate with the rear end of the case of cased ammunition located in the firing chamber of the cannon to seal the rear end of such chamber off when the cannon is in the firing position, and a second one which is adapted in the operative position to trap a sealing member in engagement with the said rear end of the firing chamber. It will be appreciated that a cannon with such a breech will be able to fire both cased and uncased ammunition simply by employing the appropriate sliding block in the breech of the cannon. Further according to the invention the sealing member includes a substantially semi-ball shaped plug which can fit removably into the rear end of the bore of the firing chamber, the plug including over its outer circumference sealing means for releasably engaging the inside rim of the said bore. Preferably the sealing means comprises a so called De Bange obturation system. Further according to the invention the sealing member includes a centrally located axially extending hole which communicates with the inside of the firing chamber when the plug is located in its bore, the said hole providing a path or flash channel through which a propeilant charge located in the firing chamber can be ignited. Still further according to the invention the sealing member is connected to one end of an elongated lever of which the other end is pivotally connected to the cannon breech ring. With this arrangement the sealing member can be swung pivotally from one or operative position where the plug is located in the bore of the firing chamber, to a second or inoperative position where it is located outside the breech of the cannon. It will be appreciated that such an arrangement provides for an increase in the firing rate of such a cannon to a level comparable with that of a conventional cannon intended for firing caseless ammunition. Preferably the said free end of the lever is mounted on a transversely extending shaft of which the ends are rotatably mounted on or in the breech ring of the cannon. The invention also includes within its scope a method of converting an existing conventional cannon which is either of the type capable of firing cased ammunition only, or of the type capable of firing caseless ammunition only, to one capable of firing both types in the manner set out above, as well as to a cannon which has been so modified. It will be appreciated that because of the relatively simple modifications which are required, the arrangement lends itself to a very rapid conversion of such a conventional cannon to a cannon according to the invention. The invention will now be described further by way of example with reference to the enclosed drawings in which: Figure 1 is a diagrammatic longitudinal section through the breech and associated parts of a conventional cannon adapted for firing cased ammunition only, the sliding block of the breech being shown in the operative position; Figure 2 is a similar view as that of figure 1 of one embodiment of a breech according to the invention, shown in the operative position; Figure 3 is a similar view as that of figure 2, with the breech shown in the in-operative position; and Figure 4 is a diagrammatic perspective view of the breech of figure 3. Referring to all the drawings, the breech mechanism 10 of a cannon comprises a breech ring 1 1 which defines a trough like elongated channel 1 2 of which the one end communicates with the rear end of the bore of the firing chamber 1 3 of a cannon of which the rest of the details are not shown. In the arrangement shown in figure 1 , breech mechanism 10 is that of a cannon intended to fire cased ammunition 14 only. Such ammunition can be loaded via channel 1 2 of breech ring 1 1 into firing chamber 1 3 so that the rear end 1 5 of the case 1 6 of ammunition 14 engages the surrounds of the bore of chamber 1 3 from where it can be extracted by the lug 1 7 of an extractor 1 8 after a shot had been fired. Breech mechanism 10 of the embodiment of figure 1 includes a conventional type sliding block 1 9 which is reciprocally slidable in the direction of arrow 20, i.e. transversely relative to the longitudinal axis of chamber 1 3, from a first or operative position shown in figure 1 , to a second or inoperative position similar to that shown in figures 3 and 4 for a sliding block 21 . When block 1 9 is in the operative position shown in figure 1 , its leading end frictionally engages the rear end 1 5 of case 1 6 to support it and to cooperate with it to seal off the rear end of the bore of chamber 1 3 while the cannon is in the firing position. When the shot had been fired, block 1 9 slides to its inoperative position and at the same time case 1 6 of the spent ammunition is ejected by the lug 17 of extractor 18 from chamber 13 via breech ring 1 1 . The cannon can then be reloaded in conventional manner. In the arrangement shown in figures 2 to 4, in which some of the details of lug 1 7 and extractor 1 8 have been omitted for clarity purposes, a modified block 21 is provided which, similar to block 1 9, is reciprocally movable in the direction of arrow 22 between its operative position, shown in figure 2, and its inoperative position shown in figures 3 and 4. In this arrangement, which is intended for utilisation in a cannon which can fire both cased and caseless ammunition, sliding block 21 is of such width that when it is in its aforesaid operative position (figure 2) it can trap a sealing member 23 in the mouth of the rear end of the bore of firing chamber 1 3 to seal the latter off while the cannon is in the firing position. Sealing member 23 comprises a substantial semi-ball shaped plug 24 which can pass into the bore of chamber 1 3 and which is provided over its outer circumference with a sealing system 25 of the so called De Bange obturation - type which can sealingly engage the inside rim of the mouth of the bore of chamber 13. Plug 24 is connected to one end of an elongated lever 26 of which the other end is connected to a shaft 27 of which the ends are rotatably contained between two spaced apart protrusions 28 mounted on the upper face of breech ring 1 1 . It will be appreciated that in an alternative arrangement the ends of shaft 27 may be contained rotatably within breech ring 1 1 . Sealing member 23 is hence pivotally movable from a first or operative position shown in figure 2, where it seals off the mouth of the bore of chamber 1 3 when the cannon is in the firing position, to a second or inoperative position, shown in figures 3 and 4, where it is located outside breech ring 1 1 when the cannon is not in the firing position. Sealing member 23 includes a centrally located passage 29 which serves as the flash channel through which the propeilant charge located inside chamber 1 3 can be ignited when the cannon is fired. It will hence be appreciated that when the cannon of figures 2 to 4 is intended to fire cased ammunition 14, sliding block 1 9 is employed with sealing member 23 being pivoted to its inoperative position. When the cannon has to fire caseless ammunition, block 21 and sealing member 23 are utilised in the manner described above. Because of the simplicity of operation of such a sealing member 23, the firing rate of a cannon utilising it is more rapid than that of the conventional type of cannon intended for firing caseless ammunition. It will be appreciated that apart from including such a dual purpose breech system on newly manufactured cannons, existing cannons may also be modified to incorporate such sliding blocks 1 9 and 21 and sealing member 23. For this purpose such sliding blocks 1 9 and 21 and sealing member 23 may be supplied as a loose kit. It is also intended for the scope of this invention to extend to such a kit. Because of the ease and simplicity with which such a kit can be fitted to an existing cannon of the cased or caseless type, the conversion can be effected very rapidly. It will be appreciated further that there are no doubt many variations in detail possible with a breech for a cannon, a cannon, a kit and method according to the invention without departing from the spirit and/or scope of the appended claims.

Claims: 513 CLAIMS CLAIM 1 A breech for a cannon which includes two interchangable sliding blocks, a first one which can in conventional manner in the operative position support and cooperate with the rear end of the case of cased ammunition located in the firing chamber of the cannon to seal the rear end of such chamber off when the cannon is in the firing position, and a second one which is adapted in the operative position to trap a sealing member in engagement with the said rear end of the firing chamber. CLAIM 2 The breech of claim 1 wherein the sealing member includes a substantially semi-ball shaped plug which can fit removably into the rear end of the bore of the firing chamber, the plug including over its outer circumference sealing means for releasably engaging the inside rim of the said bore. CLAIM 3 The breech of claim 2 wherein the sealing means comprises a so called De Bange obturation system. CLAIM 4 The breech of any one of the preceding claims wherein the sealing member includes a centrally located axially extending hole which communicates with the inside of the firing chamber when the plug is located in its bore, the said hole providing a path or flash channel through which a propeilant charge located in the firing chamber can be ignited. CLAIM 5 The breech of any one of the preceding claims wherein the sealing member is connected to one end of an elongated lever of which the other end is pivotally connected to the cannon breech ring. CLAIM 6 The breech of claim 5 wherein the said free end of the lever is mounted on a transversely extending shaft of which the two opposite ends are rotatably mounted on or in the breech ring of the cannon. CLAIM 7 A breech for a cannon substantially as herein described and as shown in figures 2 to 4 of the drawings. CLAIM 8 A method of converting an existing conventional cannon which is either of the type capable of firing cased ammunition only, or of the type capable of firing caseless ammunition only, to one capable of firing both types, substantially as herein described. CLAIM 9 A cannon which is adapted to fire both cased and caseless ammunition, substantially as herein described. CLAIM 10 A kit for converting a conventional cannon which is either of the type capable of firing cased ammunition only, or of the type capable of firing caseless ammunition only, to fire both cased and caseless ammunition, the kit comprising two interchangeable sliding blocks and a sealing member substantially as herein described.

Inventors: MUELLER ERNST JOHANN HEINRICH, MUELLER, ERNST, JOHANN, HEINRICH
Applicants: DENEL PTY LTD, KISCH OCTROOIBUREAU, MUELLER ERNST JOHANN HEINRICH, DENEL (PROPRIETARY) LIMITED, MUELLER, ERNST, JOHANN, HEINRICH, OCTROOIBUREAU KISCH N.V.
Application year: 1994
Main classification: F41A3
IPC codes: F41A3, F41A11